<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8" />
		<title></title>
	</head>
	<body>
		
		<input id="aaa" />
		<script type="text/javascript">
			document.getElementById("aaa").onclick = function(){
				alert(1)
			}
			setTimeout(function(){
				document.getElementById("aaa").onclick();
			},1000)
		</script>
	</body>
</html>